Conventional wisdom holds that -- on standardized tests -- when test-takers aren't certain, they should stick with their first choice of answer and not change it. Research being released today by the Educational Testing Service challenges that assumption. ETS studied 8,000 test-takers worldwide on the GRE, and found that of those who changed answers on the quantitative reasoning section, 72 percent saw scores increase, while of those who changed answers on the verbal reasoning section, 77 percent saw scores increase. At the same time, ETS surveyed test-takers and find that they still tend to believe they shouldn't change their answers, with 59 percent saying that they believed that their first answer was more likely to be correct than a changed answer.